The journal of pain : official journal of the American Pain Society
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Central sensitization is considered to have a pathophysiological role in chronic low back pain (LBP). Whether individuals with increased central sensitization early in their condition are more likely to develop persistent pain or whether it increases over time is unclear. This study aimed to determine whether sensory profiles during acute LBP differ between individuals who did and did not recover by 6 months and to identify subgroups associated with outcomes. ⋯ Two subgroups were identified that associated with more ("high sensitivity") or less ("high sensitivity and negative psychological state") recovery. These data seem to suggest that central sensitization during the acute phase resolves for many patients, but is a precursor to the transition to chronicity when combined with other psychological features. PERSPECTIVE: Central sensitization signs during early acute LBP does not necessarily precede poor outcome, but may be sustained in conjunction with other psychological factors and facilitate pain persistence.
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Spatial integration of parts of the body is impaired in patients with complex regional pain syndrome (CRPS). Because the training of mental rotation (MR) has been shown to be among the effective therapy strategies for CRPS, impairment of MR is also important for the pathophysiological understanding of CRPS. The aim of this study was to evaluate whether differences in the neural representation of MR occur between patients with CRPS and healthy controls (HC). ⋯ Regression analysis for the CRPS group emphasized the importance of putamen and nucleus accumbens activation for MR performance. This study highlights the reduced access of patients with CRPS for mental resources modulating arousal, emotional response, and subcortical sensorimotor integration. PERSPECTIVE: This study localized the underlying neural responses for impaired mental rotation in patients with complex regional pain syndrome as a decrease in basal ganglia (putamen) and nucleus accumbens activation.
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The present study investigated the role of the amygdala N-methyl-d-aspartate (NMDA) receptors/nitric oxide synthase pathway in morphine-induced anti-allodynia. Concurrently with the bilateral cannulation of the central amygdala, chronic constriction of the sciatic nerve was performed on male Wistar rats. Morphine (3-5 mg/kg) was administered intraperitoneally to induce anti-allodynia. ⋯ PERSPECTIVE: Neuropathic pain is difficult to treat and the exact mechanisms remain unknown. This article suggests the importance of the amygdala glutamatergic and nitric oxide systems in morphine-induced anti-allodynia. These findings might be used in clinical studies to reach a better understanding of neuropathic pain mechanisms and treatment.